The object of this invention is concerned with the seat portion of an ergonomic chair. The intention is to allow the pelvis to move in reciprocating gliding motion rather than forcing the pelvic bones to compress on a stationary cushion or seat, thus reducing postural instigated lower back pain.
Sitting in a standard chair seat, whether it is cushioned, metal, wood or plastic single piece chair seat, does not allow the three pelvic bones to move. Weight distribution on the pelvis is through the sits bones, known as the ischial tuberosities, and not the central sacral bone. The skeletal system of the human body is a functional, biomechanical structure moved by muscles and supported by ligaments. Skeletal bones are not only moved by muscles yet influenced by the rhythmic waves of circulation, digestion, lymph and cerebral spinal fluid flows. Therefore, the skeletal bones are constantly in motion. They allow other fluid systems to function by internally and externally rotating around the center axis of the body. Heart rate and peristalsis can be measured by listening to these systems through a sphygmomanometer listening device while the hydraulic cerebro-spinal fluid movement by the movement of the skeletal structures. This movement is dependent on the pitch (flexion-extension), roll (lateral flexion-extension and yaw (internal-external motion on a vertical axis) of the skeletal structures. The skull, spinal column and the sacral bone of the pelvis house the cerebro-spinal fluid system. There exists in this closed hydraulic a flow of cerebro-spinal fluid that is essential for neural activity.
The cerebro-spinal fluid originates in the in the ventricles in the center of the skull and travels through the lower back into the sacral reservoir. The movement of the pelvis when walking aids in the movement this fluid, along with with the assistance of the dural sheaths, back up the spine and into the skull. Any impediment of this fluid flow results in a stasis of cerebro-spinal fluid in the lower back. It is this loss of motion, stasis and accompanying neural root irritation that leads to muscle compression resulting in lower back pain and stiffness when one must sit or stand for long periods of time in or on a static seat. If a chair seat is to address this problem, the seat must support the two sides of the pelvic bones (ilia) independently and allow gliding movement to assist the normal range of motion of the pelvis and lower back.
All seats are motionless and do not allow pelvic motion to occur. Based on the premise that the structure of the pelvis influences the function of cerebro-spinal flow, it is important to maintain adequate motion of the three pelvic bones, the two iliac bones and the sacrum.
The intent of the Spinal Glide ergonomic chair seat is to enhance cerebrospinal fluid motion by allowing or enhancing the pelvic ilia to glide in movement while one is seated in the Spinal Glide seat or standing on the Spinal Glide standing apparatus. The seat and the standing apparatus are the same invention, it can be used for either sitting or standing, only the supporting structures are different.
Chairs with moving seat elements, which may be motorized or otherwise driven for the purpose of relieving fatigue and stimulating some of the hip motion of walking, have been known. Harza U.S. Pat. No. 5,588,704 shows a rocking platform incorporated in a seat, causing one hip to be lifted and then the other in a rhythmic manner while the person is seated. The disclosed apparatus also allows for forward and backward gliding movement of each hip. Harza U.S. Pat. No. 5,022,385 is directed at a similar goal, but using air bags and a pneumatic pump for vertically moving the two hips up and down in opposition.
Other patents which show power seat mechanisms, but not with the purpose of hip and pelvic motion, include U.S. Pat. Nos. 5,314,238, 5,709,363, 5,735,573 and 5,751,129. Specific patents pertaining to the motion of the pelvis are Brightbill et al. U.S. Pat. No. 5,913,568 addresses as stated only the vertical motion and rocking motion sufficient to allow pelvic motion from a horizontal plane, it differs from the disclosed apparatus because the Spinal Glide seat has a specifically raised central platform of ¼ to ½ inch. In order for the pelvis to adequately rock there most be a solid, raise platform to fulcrum over. With the raised platform with springs or rubber balls, there is not a rocking motion yet a forward and backward gliding motion of the seat. Not the rocking, and vertical motion cited by Brightbill et al. Yet where Brightbill limits the seat motion to vertical motion and horizontal rocking, the Spinal Glide seat includes rolling laterally, yawing motion to allow for twisting movement and also allows an opening of the ischial bones to alleviate pressure on the sacral bone when one is seated in an erect position.
It one is to address range of motion of the pelvis, they must consider a device that includes pitch, roll and yaw movement. Brightbill also consider pneumatics to be placed under there seats, yet Harza's patent originally included the alternating motion pneumatic motion. Spinal glide utilizes springs, rubber balls and like pole magnets to allow for the pitch, roll and yaw movement.
Berg's patent; Berg et al. U.S. Pat. No. 5,024,485 allows a rocking motion yet without a raised platform under the central movement. They also specifically state in column 2, line 64-66 that their movement addresses one horizontal plane by stating “only back and forth movement in a horizontal rocking motion as opposed to universal movement.” Also, all of the patents mentioned do not include any standing position apparatus or recommendations which allow for pelvic motion in a standing position.